History of the Peloponnesian War

Now as many of us as have already had any dealings with the Athenians require no warning to beware of them; but those who live more in the interior, and not in the high way of communication, ought to know, that if they do not defend those on the coast, they will find the carrying down of their produce [for exportation] more difficult, and the procuring again of those things which the sea affords to the mainland; and they ought not to be indifferent judges of what is now said, as though it did not affect them, but to consider that some time or other, if they should sacrifice the towns on the coast, the danger would reach even to them; and that they are now consulting for themselves no less [than for others].